A Co-ordinated Radio Access Network (C-RAN) is a group of sites or nodes working in coordination in a Long-Term Evolution (LTE) network to improve network performance. One of the features of the C-RAN is Uplink Coordinated Multipoint (UL-CoMP). As a part of this feature, uplink performance of the mobile device to the network can be improved. To this end, the C-RAN type network may include multiple towers/sites and a receiver shared among the multiple towers/sites. The multiple towers/sites use their respective radio connectivity path to the mobile device to allow the mobile device to transfer the radio frequency (RF) signal to the receiver. To this end, in addition to the primary connection via the first tower/site to the mobile device, the receiver also includes a secondary connection via a second and different tower than the first tower to the mobile device. This way the receiver can receive the RF signal from the primary connection associated with the first tower and can receive the same RF signal from the secondary connection associated with the second tower and can use both signals for interference cancellation and decoding to improve uplink performance.
The limitation on the receiver side to be able to make use of connection paths provided by the multiple towers/sites is that the difference in RF time delay associated with the paths may not exceed more than the network cyclic prefix. In one specific example, the network cyclic prefix may correspond to 4.7 microseconds, which in turn corresponds to 1 km. However, the network cyclic prefix may be more or less that 4.7 microseconds in other implementation. The period defined by the network cyclic prefix is a period in which the receiver scans for incoming signal.
The limitation that the distance cannot exceed the cyclic prefix poses practicality issues because the difference in actual distance of paths can exceed 1 km. Hence, a need exists for a method to take advantage of the C-RAN network offerings even in the scenario whether the difference between the distances of the paths to multiple towers exceeds the cyclic prefix.